Epidemiology and Molecular Typing of Pregnancy-Associated Listeriosis Cases in Lombardy, Italy, over a 10-Year Period (2005–2014)

In developed countries, pregnancy-related listeriosis accounts for 20\u201343% of total invasive listeriosis. This work describes the first pregnancy-related listeriosis survey in Italy based on two data sources, that is, mandatory notification system and regional laboratory-based network. Out of 610 listeriosis cases reported over a 10-year period, 40 were pregnancy-related (6.6%). Among these, 29 pregnancy-related isolates were available and have been analysed with serotyping, Pulsed-Field Gel Electrophoresis, and Multi-Virulence-Locus Sequence Typing. No maternal fatality was recorded, but 11 (29.7%) pregnancies resulted in a foetal death, a miscarriage, or a birth of a foetus dying immediately after birth. The average incidence of pregnancy-related listeriosis was 4.3 cases per 100000 births, and the proportion of pregnancy-associated listeriosis among ethnic minorities was significantly higher compared to the general population (30.0% versus 3.5%, ). L. monocytogenes isolates belonged to serotypes 1/2a, 1/2b, and 4b, with the latter significantly more prevalent among pregnancy-related isolates. Twenty different pulsotypes were distinguished and 16 out of the 29 isolates were classified into seven clusters. A total of 16 virulence types (VTs) were identified. Five VTs accounted for 45% of the total cases and coincided with those of previously described Epidemic Clones (ECs) of L. monocytogenes

Whole-genome sequencing and comparative genomic analysis of Salmonella enterica serovar Napoli strains isolated from human cases occurred in Lombardy and Emilia-Romagna, Northern Italy

Background: Salmonella enterica serovar Napoli (S. Napoli) is uncommon in Europe except in Italy, where it ranks among the top five serovars causing human infection. However, information about its epidemiology, ecology and virulence is poor, and no foodborne or environmental factor has been identified so far. Importantly, recent studies conducted by our group have revealed that S. Napoli and typhoid serovars are highly related, in terms of genomics and clinical characteristics. Material/methods: Forty-four S. Napoli strains isolated from human cases in Lombardy and Emilia-Romagna, Italy (2012-2014), were subjected to whole-genome sequencing (WGS) using the Illumina MiSeq platform. Bayesian SNP-based phylogeny was reconstructed using the kSNP software. A comparative genomic analysis was performed to detect the differences between the S. Napoli genomes, in terms of nucleotide variations. Results: Phylogenetic analysis revealed that S. Napoli isolates are grouped in two main clades that strongly correlate with their geographic origin (Figure 1). Clade A (n=16 isolates) included most of the isolates from Emilia-Romagna, and clade B (n=28 isolates) comprised most of the isolates from Lombardy, including the strain SMOUT310_MI, responsible for causing a recent outbreak in Milan (2014). Conclusions: In the present study, we compared S. Napoli isolates from two different Italian regions by SNP typing based on WGS. The results indicate that WGS coupled to SNP-based phylogeny seems an excellent approach to infer the genomic and geographic distribution of serovar Napoli isolates, and that our analysis can provide valuable supplemental information about this emerging public health concern in Italy. Future studies are needed to further improve the usefulness of WGS analysis, in particular regarding genetic changes over time and diversity within regions, in order to make hypothesis regarding the origin and the geographical dispersion of this poorly studied serovar